Today, my boss brought us some small cakes from a recent trip to China. I opened mine and noticed a little foil packet wrapped with the cake, so I thought it was a powdered topping. I had a couple of bites before my coworker told me it was actually a desiccant to keep the cakes fresh. FML

It's probably best to avoid the cake altogether. The white powder is actually a preservative, as you said, but the flour is just ground up caryopsis, or grain, which was a seed to preserve the species from which it was harvested. The milk that was taken from a cow was intended to preserve its calfs, and the eggs were chicken menstruation—failed attempts to copulate and preserve the chicken lineage. If you think about it, /all/ is preservation…
Well, have a nice day!

It is real silver leaf, and it's fine. Silver is non reactive in your digestive system. It just goes right through. The only time you'd be in trouble is if you were eating big balls of the stuff and it blocked you up. Silver leaf is thin as tissue paper though.

Being that silver is about $17.50 per ounce right now I'm surprised that is an economical choice of preservative. Granted, that is why silver was the metal (and then plating) of choice well up into the 1950's due to its antimicrobial properties. Silver if still used in making acupuncture needles.

It's probably best to avoid the cake altogether. The white powder is actually a preservative, as you said, but the flour is just ground up caryopsis, or grain, which was a seed to preserve the species from which it was harvested. The milk that was taken from a cow was intended to preserve its calfs, and the eggs were chicken menstruation—failed attempts to copulate and preserve the chicken lineage. If you think about it, /all/ is preservation…
Well, have a nice day!

I'm actually kind of surprised that people don't know what those packets are. Lots of food comes with those little preservative packets in them, and lots of bottled medicines do as well. Heck, I've had shoes that had those tucked inside. I'm not blaming the OP, I'm just genuinely shocked that someone could go through life without running into those.
For future reference: if something is sealed, and you don't know what it is- don't open and eat it.